Propeller governor



Sept. 14, 1948. C. w. cHlLLsoN 2,449,452

4 PROPELLER GOVERNOR med umh l15, 1939 4 sheets-sheet 1 INVENTQR Cms/Rus MCHJLLsoN Sept 14, 1948. c. cHILLsoN 2,449,452

PROIELLER GOVERNOR INVENTOR CII/JRLES M'fmsoN ATTORNEY Sept. 14, 1948. c. w. cHlLLsN 2,449,452

PROPELLER GOVERNOR Filed arch 15, 1939 4 sheets-'sheet s INVENTOR @49u55 MOV/Lsozr MTORNEY ISept. 14, 1948. c. w. cHlLLsoN 2,449,452

PROPELLER GOVERNOR Filed March 15, 1939 4 Sheets-SheetV 4 Petented Sepe-14, 194s rRoPELLEn GOVERNOR -Charles W. Chlllson, Clifton, N. J., asslgnor to Curtiss-Wright Corporation, a. corporation ofY Delawarel Application March 15, 1939, Serial No. 261,879

13 Claims. l

This invention relates to control and governing mechanisms for controllable pitch aircraft propellers, the particular embodiment of the invention chosen for illustration being applicable to electrically operated controllable pitch propellers of the type disclosed in Patent No. 1,951,- 320, issued March 13, 1934, to W. J. Blanchard.

ontrollable pitch propellers are now beingprovided with a governor by which pitch settings oi the propeller are increased or decreased in rebe transmitted intermittently to the propellerv control motor, the dwell of the intermittent pitch changing impulses decreasing as the propeller approaches the desired pitch setting.

a Still another object is to provide a governing mechanism which will operate automatically to sponse to tendencies of the engine to gain or lose R. P. M. from a pre-set standard, whereby the propeller maintains constant speediat any desired setting oi the governor.

An inherent characteristic of a speed regulate` ing system such as the constant speed governor,

controllable pitch propeller, airplane engine combination where the rate of pitch change is essentially constant regardless of the magnitude of the pitch correction being made, and where there is an appreciable time lag between the application of the correction and the responses of the propeller due to enginev and propeller inertia, is that for a given substantially constant rate of correctionl and a definite time lag relationship, there will be a definite maximum governor sensitivity which the system will tolerate without developing hunting characteristics. r

With the growing need for rapid pitch change to prevent over and under speeding with rapid throttle `changes or abrupt changes in flight regime, combined with the importance of` synchronizing engines` closely on multi-motor installations, it has become desirable ito provide some means for speed control other than a simple single sensitivity governor. For this reason, a "proportional type of control has been developed which supplies pitch corrections in response to speed variations in increments,A the magnitude of which are proportional to the speed variation. This not only provides a closer speed control but permits the use of a higher basic rate of pitch change without causing hunting.

An object of this invention is to provide a governing mechanism for a controllable pitch propeller which shall produce pitch lchange im- A further object is to provide such a governor arrangement particularly applicable to propellers whose pitch is controlled electrically.

Another object of the invention is to provide a governonmechanism whose control action may effect either increase ordecrease in propeller blade pitch.

t Additional objects comprise the use of a hydraulically controlled electric governor unit and the provision of a hydraulic pressure responsive switch controlling propeller response to the gov-- ernor, whereby failure of hydraulic pressure will lockl the propeller in iixed pitch in or at normal operating range.

a' Further objects of the invention comprise the particular construction of a governor mechanism, the features of which will be pointed out in the annexed detail description in connection with the drawings, in which:

Fig. i is an elevation of apart of a controllable pitch propeller as mounted upon an engine nose, the latter being partlyin section to show the propeller governor drive; Y

Fig. 2 is a wiring diagram of the electrical circuit involved in the system;

Fig. 3 is an enlarged elevation of the propeller governor in the same aspect as is shown in Fig. 1,

partly broken away. and partly in section, to show certain of the details of construction;

Fig. 4 is a plan section, broken away in part, of the governor;

Figs. 5. 6 and 'I are sections. respectively, on the lines 5 5, 6 6 and 1--1 0f Fig. 4;

Fig. 8 is a plan of the governor, and

Fig. 9' is an enlarged detail section through a portion of the governor mechanism. Y

4Reference may first be made to Fig. 1, in .which l0 designates a propeller hub carrying blades I`I mounted for pitch changing rotation and carrying a power unit i2. the latter comprising an electric motor I3 and speed reducers I4 and I5 connected by gears, not shown, to the blade roots. The elements l0 to l5, inclusive, along with a slip ring assembly` I6, are generally similar to tem. The engine pressure oiling system provides to the governor mounting pad I8.

Fig. 2 shows the wiring system for the prolow engine R. P. M.. the opening 84 is covered and the annular groove 8l of the valve stem may uncover the bore of the sleeve 8| as` at 13, to

like.

peller. the dot-dash line block 28 representing '-the automatic control unit. Connections from the manual control unit 3| to the propeller are conventional in character, the control unit having a master switch 22 contactible with a switch point 33 to place the circuit in readiness for selective pitch increase or decrease through the switch 34.

The switch 32 may also be engaged with the point 88 which disconnects the manual selective control and places the governor unit i8 in circuit, this circuit including a switch 38 responsive. as will be described hereafter. to oil pressure and consequently tor engine operation. The unit also includes an oscillatable` switch arm 31 contactible with switch points 38 and 38 to decrease or increase propeller pitch respectively, the switch unit 81-88-88 beingl governor controlled, as will become apparent.

Reference may now be made to Figs. 3 to 9. which show the details of construction of the governor i8. Referring particularly to Fig. 7, it will be seen that the governor driving connection 28 comprises a sleeve rotatable in a bushing 42, the sleeve terminating in a governor plate43 on which flyweights 44 are plvoted at 48, the fiyweights being connected to a ring 48 secured to the outer race of'a ball thrust bearing 41, the inner race of which is secured by the nut 48 to a valve stem 48. The vertical position of the valve stem is accordingly controlled by the"posi tion of the ilyweights 44 which. of' course, makes the vertical position of the valve stem speed responsive. A spring 88 counteracts radial displacement due to centrifugal force in the ilyweights 44 and the force imposed by the spring upon the governor is adjustable by turning a lever 8i mounted on a shaft 82 having an integral pinion meshing with a rack 83 which forms the top abutment for-the spring l88. 'I'his adjustment is mounted in a housing 84 which forms a cover for the governor.

The pressure oil conduit 28 previously reierred to terminates adjacent the mounting pad on the engine and registers with a segmental groove` 58 (Fig. 7) at the mounting face of the governor, drillings leading .therefrom to a safety .twitch cavity t1 through a drilling ss. Another drilling 88 leads from the groove 88 to the upper part of the bushing 42 through a hole in which the loil may pass to anannulus 88 `formed in the sleeve 8| driven by the element 28. This sleeve has a drilling 84 through which oil may-pass to an annular groove 85 in the valve stem 48 when the latter is raised by the governor ilyweights. Oil may ilow through the annular groove to lower radial drillings 88 in the sleeve 8| which communicate with a set of passages 81 leading to a cylinder 88 having therein a spring-pressed piston 88. the stem of which is borne in avbushing 18 and extends into a switch box 1i to carry the switchl arm 31 indicated in the wiring diagram and shown more clearly in Fig. 3. When the valve stem 48 assumes a low position due to permit oil to bleed from the cylinder 88 to the engine crankcase. The stem and sleeve units 48 and 8| thereby comprise a governor controlled hydraulic valve which will control the position of the switch arm piston 88 in accordance with engine R. P. M. as selected by adjustment of the governor spring control arm 8|. Any variations in enginespeed will find response in the position of the valve stem 48 and thus in the position of the piston 88.

Referring now to Fig. 3, it will beseen that the stem 0i' the piston 88, designated 14, is embraced by a spring 18 abutting at its ends upon slidable washers 18 and 11 abutting shoulders on a sleeve assembly 18. the washer 18 also abuttlnga lower shoulder on the stem 14 and the washer 11 abutting a cylindrical nut 18 screwed upon the stem 14 with respect to which the sleeve assembly 18 is slidable. By this construction. the spring 18 holds the sleeve 18 in a normally fixed position, but if the sleeve be positively reciprocated with respect to the valve stem 14, the spring provides a resilient centralizing force regardless of the direction of displacement of the sleeve. The sleeve 18. as` is apparent, carries the switch arm 31 in insulated relation thereto, the arm being provided with appropriate contact pieces 88.

Mounted in the housing and projecting into the box 1i is a reciprocable plunger 82. as shown in Figs. 3 and 5. this plunger carrying the contacts 38 and y38 in insulated relation thereto and and to each other through bushings 83 secured by a nut 84. The contact pieces 88 and 38 are engageable in` a manner later to'be described with the contacts 88. The plunger 82 carries. at its lower end, a roller 88. the plunger being reciprocable in a bushing 88 secured from rotation'by a dowel 81 and anchored to the deck of the box'1i by a plate 88 and screws 88 (Fig. 4). 4The plunger is prevented from rotating in the bushing 88 by the engagement of the roller pin 88 in a slot 8l in the bushing. The roller 85 engages a cam 82, being spring-pressed toward the cam by a spring 83 within the bushing. Said cam is provided with a projecting lobe 84 and a depressed lobe 88. and is carried upon a shaft 88 Journaled in the housing and having a worm wheel-81 driven by a worm 88 on the upper end of the shaft oi' which a pump gear 88 (Figs. 4, 5 and 6) is secured. The gear 88 meshes with a gear |88 secured to theengine driven sleeve 8|, the gears 88 and |88 comprising a scavenging oil pump. the nature of which will be described shortly. It will be apparent, however, that the camshaft 88 with its cam is driven by the sleeve 8l so that the plunger 82 is reciprocated up and down in proportion to engine speed. The dwell of the cam follower on the concentric portions of the cam holds the contact-.pieces 38 and 38 in neutral position, whereas, when the cam follower rises on the lobe 84 and drops into the .lobe 85,

` successive downward and upward movements are in the propeller regardless of the amount of pitch change that may be necessary. The intermittent action of the governor has the eilect of producing 'continuous .energization of the propeller pitch motor when the pitch' change to be made is large, but has the effect of intermittently energizing the motor when the pitch change to be made is small. The accomplishment of this function will be apparent when it is realized that the position of the contact points is always determined in response to engine R. P. M. and to the setting of the lever When the propeller pitch is at such a setting that propeller load is proper for a certain engine speed and power output, the contacts 80 will be centralized betweenthe contacts 38 and 39 which, despite 'their continual reciprocation will not engage the contacts 00. So soon as the propeller R. P. M. departs from that established yby a proper balance of the governor,

the governor will change position and willeither raise or lower the contacts 80, whereupon one or the other of the reciprocating contacts 30 or 39 will intermittently engage contact 80 to intermittently energize the propeller pitch motor, to operate same for the purpose of altering the propeller pitch to re-establish the R. P.y M. balance. If the deviation from normal is pronounced, one of the contacts 00 may ride the contacts 38 or 39 throughout an entire reciprocative movement, the spring 'l5 associated with the carrier of the con-V tacts 80 permitting of this continual contact. As propeller pi-tch approaches the desired pitch, the position of the contacts 30 will have been raised or lowered to shorten the contact time during reciprocations of the contacts 30 and 39 until ilnally, said contacts cease and the system again becomes balanced.

In Figs. '7 and 9 is shown the safety switch 36 which comprises a switch assembly inserted into a bore G05 in the governor housing. the two wires from the safety switch leading respectively through arm 3l to'contacts 80 and to a junction This junction plug 06 also carries plug |06. two additional wires leadingto the contacts 38 and 39, being clipped to the bushings B3 by clips |01 and |08. As shown in Figs. 7 and 9 the bottom part of the bore |05 terminates in the cavity 51 communicating with the oil pressure source, the switch comprising a piston i09 acted upon by pressure oil to raise same. The piston |09 carries an insulating bushing ||0` within'which a ball rests, the ball carrying a contact yoke ||2 raisable wi-th the piston. This piston is normally urged downwardly by a spring ||3 enclosing an insulating sleeve H4 which in turn em-` braces contact bars ||5 and ||6 axially located in the bushing H4 byinsulating pins H1, the bars being insulated from one another by a strip ||8. The lower ends of the bars ||5 and HIE are bridged by the element I I2' so that when sufllcient oil pressure exists below the piston 0 9 the switch circuit is closed. When such pressure is relieved, the element ||2 breaks the circuit of the switch. Oil relief from the switch is provided through a drilling ||9 by which leakage may ow to the governor cavity for subsequent drainage to the engine.A

to.v

power means. y 3. In a governor for an engine having a fluid provided with holes |22 to receive oil leaking past the piston and from which oil may flow through a drilling |23 in the housing, shown in Fig. 7, to the governor cavity. In Fig. 5 passage |24 supplies lubricating oil to cam 92. gears 91 and and associated journal bearings from surplus oil in the governor cavity. It also provides a pressure relief for the oil filled cam cavity against pressure fluctuations caused by the reciprocation of plunger 02.

Below the governor plate 43 referring to Figs. 4 and 6, the gears 09 and |00 are located, and the floor of the governor cavity is so formed in conjunction with a ring |28 as to provide -ahousing embracing the gears 99 and |00 to permit them to operate as a scavenging oil pump.v Oil collecting `in the governor cavity will enter the gear teeth, as shown by the arrows A, and will be carried around the gears to the point B, whereat a hole |21 is drilled in the-ring |26 to permit scavenge oil to flow into a cavity |28 connecting with a drilling |29 inthe housing which in turn discharges through a hole in the bushing 42 'as at |30 whence the oil may pass through the hollow driving sleeve to the interior of the engine crankcase.

WhileI have described my invention in detail in its present preferred embodiment, it will rbe obvious to those skilled in the art, after understanding my invention, that various changes and modifications may be made therein without departing from the spirit or scope thereof. I aim in the appended claims to cover all such modiiications and changes..-

I claim as my invention:

1. I n a governor system for an aircraft power plant including an engine and a controllable pitch propeller driven thereby, electric motor means for changing the propeller pitch, a. reciprocable switch member driven by the power plant, a second switch member engageable with the iirst, means to control the position of said second member in proportion to engine speed, said members being thereby, contactable for longer or shorter dwell upon reciprocation of the first member according to the speed responsive position of said second member, and control connections from` said switch members to said electric, motor.

2. In a governor system for an aircraft power plant, a controllable pitch propeller, power means `for changing the propeller pitch, a first member reciprocably driven by the engine, a second member intermittently engageable with the first due to reciprocation thereof, having engine speed responsive means associated therewith for positioning same according to engine speed, the engagement dwell of said members being variable according tothe position of said second member, and means `responsive to engagement of said members for energizing said pitch changing :pressure supply and a `rotating shaft, a valve `sleeve rotated by the shaft, a ilyweight governor onl the sleeve having a. valve stem movable ax-` ially in the sleeve upon change in the ilyweight positiondue to R. P. M. changes, a. conduit conducting pressure fluid to said sleeve, a. cylinderpiston assembly connected to said sleeve to receive or discharge iiuid according to the valve position in said sleeve, a switch arm carried by one element of the'pistonfcylinder assembly, a second switch arm intermittently movable toward and away from said ilrst arm, means driven by the engine to effect said intermittent motion. and

ing the speed of said engine.

4. In a governor for an engine having a fluid" pressure supply and a, rotating shaft, a valve sleeve rotated bythe shaft, a ilyweight governor on the sleeve having a valve stem movable axially in the sleeve upon change in the ilyweight position due to R. P. M. changes, a conduit conducting-pressure iluid to said sleeve, a cylinder-piston assembly connected to said sleeve to receive -or discharge iluidaccording to the valve position in said sleeve, a contact carrier on one element `oi, thepis toncylinder assembly, a cam driyen from said sleeve,v a plunger reciprncated by said cam, a second contact carrier on said plunger, a switch point on one said carrier, slow and fast switch points on the other said carrier, said ilrst switch point being contactable with one or the other of said slow and fast switch points according to the governor controlled relation of said piston-cylinder assembly, and means energized termittently energizing said lpitch changing means upon a speed variation. whereby the duration of said energizing periods is proportional to the speed variation. s

6. InV a control system for an aircraft power plant, a controllable pitch propeller driven thereby, electrical means to alter the pitch setting of the propeller, fluid pressure means-responsive to changes in the speed of the engine from a preset standard to control the electrical means, and means, responsive to the magnitude of the speed deviation from said standard for continuously altering, during the period in which the speed of the propeller is diil'erent from that desired,

' means actuated by contacts of said for alters i therewith, upon a speed variation, to intermittently energize said power means.

9. In a governor system for an aircraft power trol the position of said second switch member` in its position as a function of engine speed, one

of said switch members being yieldably mounted to allow of contact dwell of said switch members vupon overtravell thereof, said members being lthereby contactable for longer or shorter dwell upon back-and-forth movement of said -ilrst member accordingto the speed responsive 'position of said second member, and control connections from said switch members to said electrically controlled motor means.

10. In a governor system for an aircraft powerv plant, a controllable pitch propeller, power means for changing propeller pitch, a first member driven by the engine for back-and-forth movement, a lsecond member intermittently engageable with the ilrst due to said movement, engine speed responsive means associated with said second member for positioning same according to engine speed, one of said members being yieldably mounted to allow of engagement dwell of said members'upon overtravel thereof, the engagement dwell of said members being variable according to the` position of said second member. and means responsive to engagement of said members for energizing said pitch changing I means. v

11. In a governor system for an aircraft power plant, a controllable pitch propeller driven thereby. power means for changing the pitch of said the amount of electric energy per average unit of time conducted to said electrical means, thus to vary the propeller.

'1. In a speed control system for an aircraft engine-driving a controllable pitch propeller, power means for changing the propeller pitch, and means responsive to engine speed variation from a desired value to intermittently energize said pitch changing means, the duration of said energizing periods being proportional to the speed variation, said last named means .comprising iluid pressure means responsive to engine speed variation, a member movable by said fiiid pressure means in proportion to the speed variation. a second member adapted to contact said rst member to energize said pitch changing means, and means to cyclically move one of the members relative to the other.

8. In a speed control system for an engine havgine speed, a second switch contact, means for cyclically moving one of said contacts relative to the other contact for intermittent engagement average rate of pitch change of the der-piston assembly connected to said sleeve to l propeller, at least two switch contact carrying devices intermittently movable toward and away from one another. the contacts carried by said v devices being intermittently engageable, means to move one said device cyclically toward and from i the other device, means to position one said device in a plurality of positions each position corresponding to a certain engine speed, the

mounting of one contact on one -said device including a yieldable element to allow continued engagement of said contacts upon overtravel of said devices relative to each other, and means responsive to engagement of said contacts for energizing said pitch changing means.

12. In a governor system for an engine having a iluid vpressure supply and a rotating shaft, a valve sleeve rotated by said shaft, a yweight governor on the sleeve having a valve stem movable axially in the sleeve uponchange in the flyweight position due to R. P. M. changes, a. conduit conducting pressure iiuid to said sleeve, a cylinreceive or discharge iluid according to the valve position in said sleeve,- a switch member carried by one element of the piston-cylinder assembly, a second switch member movable toward and away from said rst member for intermittent-contact therewith, one of said members being yieldably mounted to allow of engagement dwell of said members upon overtravel thereof, means driven by said engine to eiect such intermittent movement, and means actuated by member contacts for altering the speed of said engine.

13. In a speed control system for an aircraft engine driving a controllable pitch propeller hav- 1118 means to change propeller pitch, the com- 9 bination of an engine driven governor presettabie to a desired engine speed, a switch arm positioned in response to governor operation, a second switch arm, one of said switchl arms being resilientiy mounted, and means for cyclically moving one o1 said switch arms toward and at times into contact and away from and .out of contact with said other switch arm to produce intermittent and variable contact dwells, upon speed deviations of said engine from the desired speed said propeller pitch changing means being responsive in its energization operation to contacts of said arms,

whereby the duration of enerlizing periods due to contact dwells is proportional to the speed deviation of said engine.

. I CHARLES W. CHILLSON.

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